ACTS (Advanced Communications Technology Satellite)

ACTS (Advanced Communications Technology Satellite) is an experimental NASA satellite that has played a central role in the development
and flight-testing of technologies now being used on the latest generation
of commercial communications
satellites. The first all-digital communications satellite, ACTS supports
standard fiber-optic data rates, operates in the K- and Ka-frequency
bands, and has pioneered dynamic hopping spot beams and advanced onboard
traffic switching and processing. (A hopping spot beam is an antenna beam
on the spacecraft that points at one location on the ground for a fraction
of a millisecond. It sends/receives voice or data information and then electronically
"hops" to a second location, then a third, and so on. At the beginning of
the second millisecond the beam again points at the first location.) ACTS-type
onboard processing and Ka-band communications are now used operationally
by, among others, the Iridium and Teledesic systems. ACTS was developed, and is managed and operated, by the Glenn
Research Center.